Electrochemical route to alleviate irreversible capacity loss from conversion type α-Fe₂O₃ anodes by LiVPO₄F prelithiation

Abstract

We report a new electrochemical procedure to suppress the irreversible capacity loss (ICL) from high capacity anodes, specifically for high capacity anodes that undergo either alloying or conversion reaction with Li. In the present work, tavorite type LiVPO₄F is used as Li-reservoir and conversion type α-Fe₂O₃ nanofibers as an anode. Unfortunately, LiVPO₄F cannot be used as the promising anode (∼1.7 V vs Li) because of its poor cycling stability, but it can be used to accommodate the desired amount of Li for ICL compensation. Accordingly, LiVPO₄F is electrochemically prelithiated (Li₁.₂₆VPO₄F) and paired with α-Fe₂O₃ nanofibers with optimized loadings. The full cell is displaying a maximum capacity of ∼755 mAh g⁻¹ (calculated on the basis of anode mass) with notable cycling profile. Before the fabrication of the full cell, half-cell studies are performed to assess the Li-storage capability at the same current rate for mass balance.